sturtevant



T. J. STURTEVANT.

SCREEN.

APPLICATION FILED FEB. 6. 1917- 1 314 547 Pate11t0dSept.2,1919.

3 SHEETS-SHEET I.

.J. STURTEVANT.

SCREEN.

APPLICATION FILED FEB. s. 1911.

PatcntcdSept. 2, 1919.

3 SHEETS-SHEET 3 Inven liar j My! flitoi'fwy.

mm mm UNITED STATES. PATENT OFFICE.

THOMAS J. STURTEVANT, 0F WELLESLEY, MASSACHUSETTS, 'ASSIGNOR TO STURTE- VANT MILL COMPANY, 015 BOSTON, MASSACHUSETTS, A CORPORATION OF MAINE.

SCREEN.

Specification of Letters Patent.

Patented Sept. 2, 1919.

Application filed February 6, 1917. Serial No. 146,996.

To all whom it may concern Be it known that I, TnoMAsJ. S'IURTE- VANT, a citizen of the United States, residing at Wellesley, in the county of Norfolk and State of Massachusetts, have invented an Improvement in Screens, of which the following description, in connection with the accompanying drawings, is a specification, like characters on the drawings representing like parts.

The invention to be hereinafter described relates to screens for grading materials, and more particularly to the type of screens employed in separators and acted upon by a jarring or vibrating mechanism to cause material tofbe graded to pass readily through the screen.

A usual form of screen hitherto used for this purpose comprises a rectangular metal frame having metal screen clothing stretched thereon and secured thereto by a multiplicity of rivets distributed at close intervals along the frame. These have been found to be objectionable for a number of reasons. Among others, manufacture of these screens was a very expensive process. A'multiplicity of holes had to be located and drilled in the frame; the drilling of the holes consumed much time; the drills frequently became broken and required replacement; a

great many rivets had to be used; the multiplicity of rivets in each frame had to be manually individually inserted in the holes in theframe; and the ends of the rivets had to be headed over individually and progressively in the riveting machine. All of this entailed great expense in time and labor and even then the rivets did not secure the screen to the frame with the desired tightness.

In use, the weightof the material to be graded on the screen, and the constant pounding and vibrating of the screens at points thereon intermediate the frame boundaries tended to pull the screen clothing from the rivets and to tear and cause it to bulge or sa objectionably downward. One object of t e present invention is to cheapen greatlythe cost of manufacture of the screen; another is to secure the screen clothing more tightly to its frame than hitherto; and still another object of the invention is to so weld the screen clothing to the frame that they are'in eflect an integral whole.

The character of the invention may be best understood by reference to the followmg descriptions of two good forms of the inventlon shown in the accompanying drawings, wherein:

igure 1 is a plan of one form of screen embodying the invention;

Fig. 2 is a bottom View of the screen;

Fig. 3 is an end elevation, on an enlarged scale, of the screen shown in Fig. 1;

Fig. 4 is a side elevation, on an enlarged scale, of the screen shown in Fig. 1;

Fig. 5 is a plan of another form of screen embodying the invention;

Fig. 6 1s a bottom view of the screen shown in Fig. 5; v

Fig. 7 is a side elevation, on an enlarged scale, ofthe screen shown in Fig. 5;

Fig. 8 is an end'elevation on an enlarged scale, of the screen shown in Fig. 5;

Fig. 9 is a plan of an endportion of the screen shown 1n Fig. 5;

Fig. 10 is a vertical transverse section taken on the line 10-1O of Fig. 9;

Fig. 11 is a plan on an enlarged scale, of a portion of. the screen shown in Fig. 1; and

Fig. 12 is a vertical section taken on the line 1212 of Fig. 11.

Referring to the drawings, and more particularly to Figs. 1 to 4', 11 and 12: The form of the invention shown therein comprises a frame of steel or other suitable metal, including longitudinal side frame members 1 of angle or other suitable form, and connected by transverse end members 3, of angle or other suitable form. The longitudinal side members may be stiffened by transverse stays 5 of angle or other suitable form, connected thereto at points intermediate the ends of the frame.

Preferably the end frame members are secured to the longitudinal members so that the flanges 3 and 3 of said end members are beneath the plane of the lower flanges of the longitudinal members, as will be noted in Fig. 4, thereby preventing obstruction to the free flow of material along and off from the end of the screen clothing.

Screen clothing 7 is stretched or! the frame, and shown herein as a fabric woven from large gage wire (Fig. 11) with meshes of substantial size, suitable for grading coarse material.

Next will be described the new and improved means for securing the screen cloth- "a. well-known electrical spot-welding ma:

chine. The parts to be welded are placed between the electrodes of the Welding machine and the electric current turned on either by hand or automatically, whereupon the metal of the parts included between the electrodes becomes heated to the welding point, at which'time the metal is soft and that of the two parts readily caused to combine and integrate, the one with the other to thus form an' integral union of the two. lVhen the metals of the frame and screen are'at Welding heat, and consequently soft the electrodes are forced in a direction 0 approach, the result being that the metal of Y the frame flows into the mesh of the screen,

fills the mesh at the spot welded and forms also to secure the frame members together at a flush and positive union, not only with the metal strips 01'' wires of the screen by integral union therewith, but by distribution of the metal throughout the mesh of the screen at the welded point. It is preferable to form the weld by electrodes of different size, one

being smal r than the other, the efiect being that the pressure exerted on the electrodes when the metal is at welding heat and soft, causes the metal to flow especially the metal of the frame which is of greater mass to cause spots 9 (Figs. 11 and 12) which extend from the frame into the mesh of the screen, producing in a sense what may be conveniently referred to as projewtions'or studs of the metal frame, whichare forced into the mesh or meshes of the screen clothing adjacent thereto and become welded to the adjacent wires of said clothing.

These spots are distributed at intervals along the side frame members. The screen may be similarly Welded at spots 12 on end members. As a result, the screen clothing and frame are welded together so as to form in effect, an integral whole.

The metal of theframe thus forced toward the screen, and which for convenience of description I have called studs, is not only welded to the wires of the screen clothing, but as stated, projects into the meshes thereof, and thus obtain a positive engagement therewith to resist pulling of the clothing from the frame. Where the wires of the screen cross each other at the welding point,

A by welding the metals under pressure there are no projections formed beyond the surface or plane of the frame or screen, such as must of necesslty be present Where the screen and frame are secured by rivets, bolts, or

aerate? solder. This is animportant feature in a screen employed in gradin fine material and gives to the screen itsel the advantage of permitting unobstructed flow of the mate rialv being screened. Thus the integration of the metal of the frame and of the screen by welding and pressing the metal parts between the electrodes, as described, gives a firm and positive union of the frame and screen and avoids all objectionable obstruction to the free flow of the material over the screen.

At the points where the side members cross and are superposed on the end and intermediate members of the frame, the

screen clothing may be introduced therebe-.

tween, and when these points are spotwelded, the studs producedmay connect and be integral wlth the superposed frame members. Thus, the studs not only serve to secure the screen clothing to the frame, but

these points.

Preferably, the screen clothing is welded,

frame, andto the screen clothing at points 13 (Figs. 11 and 12) intermediate the side members, and serve to transmit vibrations from the vibrating mechanism to the clothmg.

Referring now more particularly to Figs. 5 to 10: The form of the invention there shown comprises longitudinal side frame members 15 similar to those already described. The transverse end members 17 however, instead of being of angle form are of flat stri form.

Screen c othing 19 is stretched on this frame and may be of fine brass wire with small meshes, suitable for grading fine matcria delicate than the coarse clothing first described, and its fusing point is lower, it is desirable to interpose 'the margins of the screen between the frame members and flat binding strips 21 or other suitable members.

The frame members and strips are pressed and welded together. This may be accomplished conveniently by introducing the parts into the electric welding machine be tween the electrodes thereof. Spots 13 (Figs. 9 and 10) are engaged by said elec- Since this screen clothing is more trode become highly, heated and softened,

and studs or projections 25 in the present instance of the invention, are forced from the lower binding strips through the screen .and become welded to the frame members. -These spots may be distributed along the side and end frame members. The pressure of the electrodes in the weldmg process serves conveniently to press the side and end frame members into intimate engagement with the screen clothing, and

when the parts are welded together as described, the frame members and strips are permanently held in this close relationship. The screen clothing ma be not only held frictionally, but also posltively, by the studs or projections between the members.

To strengthen the screen and transmit and distribute the percussive vibrations thereto, longitudinal members 27 may be provided beneath the screen parallel with and intermediate the side members and welded to the end members. Strips 29 may be superposed on the screen above the longitudinal Interlongitudinal strips, ribbons 33 of canvas or other suitable material, may be introduced between said strips and the screen clothing. These ribbons are somewhat wider than said strips and desirably serve to prevent engagement of the screen clothing with the edges of said strips.

The ends of the screen clothing may be mounted on short strips 35 (Figs. 8 and 10) superposed on the end members of the frame between the side and intermediate longitudinal members. Transverse binding strips 37 may be superposed on the screen above said short strips; and the end frame members, short strips and binding strips may be spot-welded together.

Heretofore it has been the practice to purchase new screen clothin and apply it to the screen frame when the screen clothing originally on the frame is worn out, but my new means for securing the screen clothing to the frame renders it cheaper to purchase a new frame with the clothing attached than to remove the old screen clothing from its frame and apply new clothing thereto. This great reduction in the cost is due, among other things, to the fact that by my invention, no holes are drilled in the frame; no drills are used and broken; no time is conrequired.

The screen clothing is not only secured to its frame by means much cheaper than formerly used, but also the welding process presses the screen clothing engaging parts much tighter togetherthan in the riveting process, and thus a highly efiicient clamping of the screen clothing to the frame is obtained. Furthermore, there are no rivet heads projecting from the frame or clothing, but on the contrary, their surfaces are smooth and uninterrupted throughout.

It will be understood that the frame may be of various proportions and sizes, its members may be of angle or other shapes, and 1ts stay and vibration members may be variously constructed.

The expression screen clothing is not to be understood as limited to woven fabric, but is to be regarded as generic to any foramlnous structure suitable for grading material.

Having described two forms of the invent ion for purposes of illustration, without limiting the invention thereto, what is claimed is:-

1. A screen for grading or separating materials by passing the latter over the screen, comprising a metal frame having side and end members, means for securing the side and end members together, and metal screen clothing stretched on said metal frame and welded thereto, the metal of the frame at the welding points being forced into the Wire mesh of the screen and presenting no obstruction beyond the surface of the screen or frame.

2. In a screen for grading materials, the combination of a metal frame, ametal screen supported by said frame and welded thereto at intervals, the metal of the frame at the welding points being forced into the mesh of the metal screen and presenting no obstruction to the passage of materlal over the screen. v

3. A screen for grading materials comprising a metal frame having side and end members, and metal screen clothing stretched on said frame, said members having studs of metal forced therefrom positively. engaging said clothing and welded thereto for producing in effect an integral Whole.

4. A screen for grading materials comprising a metal frame having side and end members, and metal screen clothing stretched on said frame, the margins of said clothing being welded permanently to said members and in effect integral therewith.

5. A screen for grading materials, comprising a metal frame, metal members extending along said frame, and metal screen clothing stretched on said frame having portions interposed between said frame and members, said frame, screen clothing and members being welded together for producing in efiect, an integral whole.

6. A screen for grading materials, comprising a metal frame, metal members extending along said frame, and metal screen clothing stretched on said frame having marginal portions interposed between said frame and members, said frame and members being welded together through said screen clothing.

7. A screen for grading materials, comprising a frame, members crossing said frame,and. screen clothing stretched on said frame, said screen clothing being welded to said frame and crossing members by portions of metal forced from the frame and crossing members into the mesh of the screen.

prising a frame, vibration-transmitting members connected to said frame, and screen clothing having its margins spotwelded to said frame and portions intermediate said margins spot-welded to said vibration-transmitting members.

9. In a screen for grading granular material, the combination of frame members, a wire screen supported thereby, and means for integrally connecting the frame members and wire screen at intervals by ortions of the frame members extending into the meshes of the wire screen and welded to the longitudinal and transverse wires of the screen.

In testimony whereof, I have signed my name to this specification, in the presence of. two subscribing witnesses.

THOMAS J. STURTEVANT.

Witnesses:

BEATRICE 1. S ITH, NORMAN C. HUSSEY. 

